Fabrication of microprobe array with sub-100nm nano-heater for nanometric thermal imaging and data storage

A novel fabrication method of a micro-thermal probe and its array for nanometric thermal imaging and a technological approach for probe-based data storage are presented. A small metal wire for a nano-heater is fabricated at the apex of a pyramidal SiO₂ tip, which is formed by low temperature oxidation of a silicon etch-pit at 950°C, consecutive metal deposition (Pt/Cr or Au/Cr) to fill the metal into the etch-pit, and etching of the SiO₂ in buffered HF solution. Another metal (Ni) is deposited on the small wire to form a metal-to-metal junction that enables to measure the temperature at the tip end. Metal feed-through are formed on a glass substrate that is bonded with the probe array, which enables to transmit a high-speed signal to a processing-circuit and increase the probe array density. Using the thermal probe, temperature distribution on a sample surface is measured. The heating capability of nano-heater is confirmed by the resistivity change and thermophoton emission from the nano-heater when flowing a small current into the nano-heater. By using a micro-probe, preliminary experiment for data writing and erasing is performed on phase change medium.